Lingcod

Lingcod
At Santa Catalina Island, California
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Scorpaeniformes
Family:	Hexagrammidae
Genus:	Ophiodon Girard, 1854
Species:	O. elongatus
Binomial name
Ophiodon elongatus Girard, 1854
Range of the lingcod.

The lingcod, Ophiodon elongatus, is a fish of the greenling family Hexagrammidae. It is the only extant member of the genus Ophiodon.^[1] A slightly larger, extinct species, Ophiodon ozymandias, is known from fossils from the Late Miocene of Southern California.^[2]

Ophiodon elongatus is native to the North American west coast from Shumagin Islands in the Gulf of Alaska to Baja California, Mexico. It has been observed up to a size of 152 cm (60 in) and a weight of 59 kg (130 lbs).^[3] It is spotted in various shades of grey. The lingcod is a popular eating fish, and is thus prized by anglers. Though not closely related to either Ling or Cod, the name lingcod originated because it somewhat resembles those fish. The lingcod's flesh is sometimes blue-green prior to cooking. ^[4]

Life history

Lingcod are unique to the west coast of North America, with the center of abundance off the coast of British Columbia. They are found on the bottom with most individuals occupying rocky areas at depths of 10 to 100 m (32 to 328 feet). Tagging studies have shown that lingcod are a largely non-migratory species, with colonization and recruitment occurring in localized areas only.^[5]

Starting in October, lingcod migrate to nearshore spawning grounds. The males migrate first, and establish nest sites in strong current areas in rock crevices or on ledges. Spawning takes place between December and March, and females leave the nest site immediately after depositing eggs. Males actively defend the nest from predators until the eggs hatch in early March through late April. The photo to the right shows a nest-guarding male protecting his egg mass.

The larvae are pelagic until late May or early June when they settle to the bottom as juveniles. Initially they inhabit eel grass beds, then moving to flat sandy areas that are not typical habitat of older lingcod. They eventually settle in habitats of similar relief and substrate as older lingcod, but remain at shallower depths for several years.

Females and males mature at age 3–5 years (61–75 cm) and age 2 years (45 cm), respectively. Adult males can be distinguished externally from females by the presence of a small, conical papilla behind the anal vent. Up to age 2 males and females grow at similar rates, with both reaching an average length of 45 cm. After age 2, females grow faster than males, with the growth of males tapering off at about age 8, and females continuing to grow until about age 12 to 14. Lingcod live up to a maximum of about 14 years for males and 20 years for females, reaching a maximum size of approximately 90 cm and 120 cm, respectively. Off Alaska, many reach 70 pounds (32 kilograms).

Lingcod are voracious predators, feeding on nearly anything they can fit in their mouths including invertebrates and many species of fish, such as herring, Clupea harengus, salmon and Pacific hake, Merluccius productus. One of their favorite foods are smaller octopus, and they will also readily devour large rockfish. Lingcod that survive the larval stages have few predators themselves, and are vulnerable mainly to marine mammals such as sea lions and harbor seals.

Age determination of lingcod

In 1977, Dr. Dick Beamish and Doris Chilton of the Pacific Biological Station published an article showing that cross sections of the 4th to 8th fin rays from the second dorsal fin provided a method for estimating the age of lingcod^[6][7]. This method has since been validated by a mark-recapture study in which lingcod received an injection of oxytetracycline (OTC). Other methods of aging, such as those using scales and otoliths, were found to underestimate ages for older fish.

Ages are determined from fins in much the same manner as for other aging structures: sections of varying thickness are examined under a microscope, and the annuli, or rings, that are formed for each year of growth are counted and used to estimate the age. The cross sections must be made at right angles to the length of the fin ray, and it is therefore important that fins be dried flat, with the cut surface at right angles to the fin rays. In addition, the distance that the section is cut from the fin-ray base is important, and for this reason, all fins should be collected with the base intact.^[8][9]

One problem associated with using fin rays to age older fish, is that the fin-ray center may be resorbed, resulting in the loss of the first two annuli. It is therefore necessary to determine an average width for the first two annuli by examining the fins from juvenile fish. This measurement can then be used to estimate the position of the third annulus on older fish.

Gallery

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  A lingcod.

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  Lighter color variation.

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  Lingcod showing its teeth.

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  A Lingcod.

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  The skeleton of a Lingcod seen at the Monterey Bay Aquarium.

References

1. ^ "World Register of Marine Species Ophiodon Girard, 1854". http://www.marinespecies.org/aphia.php?p=taxdetails&id=240744. 
2. ^ Jordan, D.S. & J.Z. Gilbert, 1920. Fossil fishes of diatom beds of Lompoc, Stanford University. http://www.biodiversitylibrary.org/item/68104
3. ^ Froese, Rainer, and Daniel Pauly, eds. (2010). "Ophiodon elongatus" in FishBase. October 2010 version.
4. ^ "Lingcod". http://www.edf.org/page.cfm?tagID=15732. 
5. ^ DFO, 2001, Lingcod, DFO Science Stock Report A6-18
6. ^ Beamish, R.J. and D. Chilton. 1977. Age determination of lingcod (Ophiodon elongatus) using dorsal fin rays and scales. J. Fish. Res. Board Can. 27:1305-1313.
7. ^ Chilton, D.E. and R.J. Beamish. 1982. Age determination methods for fishes studied by the Groundfish Program at the Pacific Biological Station. Can. Spec. Publ. Fish. Aquat. Sci. 60: 102 p.
8. ^ Cass, A.J., and R.J. Beamish. 1983. First evidence of validity of the fin-ray method of age determination for marine fishes. N. Am. J. Fish. Man. 3: 182-188.
9. ^ McFarlane, G.A., and J.R. King. The validity of the fin-ray method of age determination for lingcod (Ophiodon elongatus). Fish. Bull. 99: 459-464.

This article incorporates material from Fisheries and Oceans Canada. This reproduction was not done in affiliation with or with the endorsement of Fisheries and Oceans Canada.